NBME Step 1 Quiz | Questions with Verified Answers & Detailed Rationale | 100% Correct | Latest 2025/2026 Update.

NBME Step 1 Quiz | Questions with i,- i,- i,- i,- i,- i,- i,-




Verified Answers & Detailed Rationale | i,- i,- i,- i,- i,- i,-




100% Correct | Latest 2025/2026 Update.
i,- i,- i,- i,- i,-




A 59F, has a 10-yrs Hx of progressive right-sided hearing loss. An
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MRI of the head shows a large cerebellopontine angle mass that
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has compressed the vestibulocochlear nn on the right.
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The mass most likely arose from which of the following cells
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types?
(Glioblasts i,-




OR
Neural crest cells)
i,- i,- i,-i,- i,- Neural crest cells i,- i,-




-Vestibular schwannomas (acoustic neuromas) i,- i,- i,-




-S-100+ *made from neural crest cells*
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Glioblasts
-Would be a glioblastoma
i,- i,- i,-




A 37M, farmworker presents to the ED b/c of a 12-hrs Hx of
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severe pain in his abdomen & legs & painful spasms of the jaw.
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,PE shows marked spasms of the maseter & abd musculature.
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During the exam, a loud noise in the exam room triggers a painful
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spasm & respiratory compromise requiring intubation.
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Administration of antitoxin prevents further symptoms, but the pt i,- i,- i,- i,- i,- i,- i,- i,- i,-



continues to require sedation & ventilatory support for the next 3-
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wks. i,-




This pt most likely has a syndrome that involves binding a toxin
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to which of the following?
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(Acetocholinesterase i,-




OR
Synaptobrevin) i,-i,- i,- Synaptobrevin
-Pt presents w/*Tetanus (lockjaw)* → presents w/
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1-Spasms of Jaw that then progress to the entire body (Chest,
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neck, back, *Abd muscles*, buttocks - may all be affected)
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2-Fever, headache, sweating i,- i,-




3-Trouble swallowing i,- i,-




4-HTN
5-Tachycardia i,-




Pathophysio i,-




-Toxin blocks inhibitory neurotransmitters *glycine & GABA*
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across the synoptic cleft → nerve impulses are not inhibited so
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,spasms occur → *Toxin cleaves Synaptobrevin II* & prevents the
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release of neurotransmitters i,- i,-




Acetocholinesterase i,-




-Botulism binds to nerves which use ACh (not esterase) → toxin
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cleaves *SNARE* proteins i,- i,- i,-




[not synaptobrevin]
i,-




The pedigrees of pts w/schizophrenia most closely resemble
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those of pts with which of the following?
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(CF
OR
DM I) i,- i,-i,- i,- DM I i,-




-Schizophrenia is more closely related to DM than to CF → pts i,- i,- i,- i,- i,- i,- i,- i,- i,- i,- i,- i,-



with schizo are 2-3 times more likely to develop DM
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A 30F, presents for a follow-up tmt of chronic renal failure &
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normocytic, normochromic anemia. Following the administration
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of recombinant human EPO, her Hb conc increases in part d/t
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increased activity of 5-ALA synthase in RBC's. i,- i,- i,- i,- i,- i,- i,-




This enzyme regulates the rxn involving the condensation of
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which of the following compounds?
i,- i,- i,- i,-

, (Glycine & succinyl CoAi,- i,- i,-




OR
Lysine & δ-ALA (5-ALA)
i,- i,- i,- i,-i,- i,- Glycine & succinyl CoA i,- i,- i,-




A 50F, with HIV presents for a follow-up. For the past 6-months,
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she has been receiving antiretroviral meds that includes the
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zidovudine, lamivudine, as well as the protease inhibitor
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nelfinavir. She is also receiving prophylaxis w/pentamidine for
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pneumocystosis & AZ for MAC. Her leukocyte count 2-wks ago i,- i,- i,- i,- i,- i,- i,- i,- i,- i,-



was 1200 (50% seg neutro's). Her plasma HIV viral load remains
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undetectable. Drug-induced BM suppression is suspected. i,- i,- i,- i,- i,- i,-




Which of the following drugs is the most likely cause?
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(Nelfinavir
OR
AZ
OR
Pentamidine i,-




OR
Zidovudine) i,-i,- i,- Zidovudine i,-




-AE BM suppression (all NRTI's) & Anemia
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-All NRTI's→
i,-